濒危植物海南风吹楠营养器官解剖结构特征

Anatomical structure characteristics of vegetative organs of endangered plant Horsfieldia hainanensis

关键词:  海南风吹楠, 营养器官, 解剖结构, 环境适应性

Key words:  Horsfieldia hainanensis, vegetative organ, anatomical structure, environmental adaptability

摘要:

该研究采用石蜡切片和光学显微技术,对海南风吹楠营养器官的解剖结构及其对环境的适应性进行了探讨。结果表明:海南风吹楠为典型异面叶,叶片中脉发达,中部分化出髓,上表皮外侧具角质层,内侧具1层内皮层,下表皮外侧无角质层,有气孔器分布,气孔器为双环型,略下陷; 栅栏组织3～4层细胞,海绵组织4～6层细胞。茎的初生结构中表皮轻微角质化,维管束为外韧型,8～10个初生维管束围绕髓排列为1轮; 茎的次生结构中,表皮外部角质层加厚,维管柱紧密排列连成环状,次生韧皮部和次生木质部发达,形成层细胞3～5层。根的初生结构中表皮细胞外壁加厚,外皮层细胞体积大,形状不规则,内侧具1层形成层,内皮层具凯氏带,初生木质部为多原型,呈辐射状排列。根的次生结构中木栓层细胞5～6层,木栓层内侧具1层木栓形成层,栓内层细胞3层。海南风吹楠营养器官具有一定耐阴和耐旱结构特征,同时与其生活的热带雨林沟谷中高温荫湿的环境相适应。

Abstract:

The anatomy structures of vegetative organs of Horsfieldia hainanensis were studied by paraffin-sectioning and optical microtechnique to explore its adaptability to environment. The results showed that the leaves of H. hainanensis belonged to typical bifacial leaf, leaf blade-midribs was well-developed and the middle part had differentiated into pith. There was cuticle on the outside of upper epidermis of leaf and one layer endodermis inside. There was no cuticle on the outside of lower epidermis, and the sunken stomata were bicyclical type distributed. There were 3-4 layer cells in palisade tissue and 4-6 layer cells in spongy tissue. In the primary structure of stem, the epidermis was slightly keratinized, and the vascular bundle was ectophloic type. The 8-10 primary vascular bundles arranged around the pith were round. In the secondary structure of stem, the outer cuticle of epidermis was thickened, vascular bundles were closely arranged into rings, the secondary phloem and secondary xylem were developed, and there were 3-5 layer cells in cambium. In the primary structure of the root, the outer walls of epidermal cells were thickened. The exodermis cells were large and irregular in shape, with one layer endodermis in the inner layer. There was casparian strip in the endodermis. The primary xylem was polyarch, with a radial arrangement. In the secondary structure of root, there were 5-6 layer cells in cork layer. There was one layer of cork cambium in the inner cork layer and three layer cells in phelloderm. The vegetative organs of H. hainanensis had a certain shade and drought tolerance structure characteristics. Meanwhile, those anatomical characteristics were adaptable to the environment of high temperature and humidity in valleys of tropical rainforest.